Touching up powdercoating

A discussion started in
1998 & continuing through 2017

(1998)

Q. Presently we use a waterbase paint for touching up our powdercoated parts with scratches. This paint isn't very durable against some commercial cleaning agents used on our product. Is there a more durable paint which could be brushed on and easily color-matched in small quantities? We are using a polyester semi-gloss powder with a small orange peel texture. Thanks for any advice you can give.

Brian M.

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A. I have been experimenting with mixing the powder with paint thinner and then brushing it on, baking it and then sanding off the excess. If you have any other ideas please let me know. The parts I am powder coating are for outside use and paint does not hold up as well.

Ed Howells

(1998)

A. We have had some success mixing a little bit of the powder we use in some Acetone [linked by editor to product info at Amazon] or M.E.K. This is good only for color though and will not reproduce texture. This mixture can be brushed or sprayed on.

Budd Black metal finishing - St. George, Utah

(1998)

A. We have found mixing powder with paint thinners to be suitable for us, although this method will not work with metallic colors. We are using polyester powder.

We send out aerosols as touch-up for minor defects of scratches during installation. The aerosols are solvent based lacquer formulations. Our customers are having problems with adhesion when applying the lacquer over the acrylic waterborne or epoxy coatings.

My feeling is that they not only use it as touch-up but also to change the entire color that is causing the problem. Is there one aerosol that will work on both the waterborne acrylic and epoxy coating? Would a primer help? What about surface prep on a job site as this is very important to adhesion?

Billy R. Hudson- Monroe, North Carolina

Repairing powder coat on Harley aluminum head and chopper frame

(1998)

Q. HELP. I RECENTLY SCRATCHED THE POWDER COATING ON THE ALUMINUM HEAD OF MY 'NEW' HARLEY-DAVIDSON. I'VE TRIED USING A PASTED ALUMINUM CLEANER WITHOUT SUCCESS. COULD YOU PLEASE RECOMMEND A REMEDY?

SINCERELY,

JEFF HOWARDTROUTMAN, North Carolina

(1999)

A. The best way to repair damaged powder coating on either a head or other powder coated components on any motorcycle is to remove the affected part and have the powder professionally removed and re-powdered. This can be done by several job shops in the United States. There are a few that can remove powder from aluminum parts and most can remove powder from steel parts without affecting the surface of the part.

Ken White

(2003)

Q. I recently scraped the bottom frame rails of my custom chopper, as I was attempting to load the low-slung motorcycle into my trailer. I know the frame is powdercoated, and totally disassembling the bike to re-powdercoat the frame is not feasible. How can I eliminate the scrapes without re-powdercoating?

James Rees hobbyist - Jonesboro, Arkansas, USA

A. Maybe no problem James. Most powder coating can be touched up with regular paint. It would surprise me if the manufacturer does not offer those little bottles of touchup paint. But if they don't, take it to a consumer-friendly powder coating shop; they will know what to do. Good luck.

Ted Mooney, P.E. RETfinishing.comPine Beach, New Jersey

February 9, 2008

Q. Hi, I drive a late model race car and we have a powder coated frame. We want to enter the car in an upcoming mall show but the frame has some flaws with the coating. I just wanted to know if there is a way to touch up the powder coating without having to strip the car completely. Thanks.

Eric Kauffman hobbyist - Reading, Pennsylvania, United States

February 12, 2008

A. Sure, Eric, most powder coating is easily touched up with liquid paint. There is not necessarily any compatibility issue. This repair may not be perfect, as earlier responders have noted, but it will improve the looks and the corrosion resistance of the scratched area. Good luck.

Method for Touching Up Powder Coating

(1999)

Q. Dear Sir,

We receive powder coated parts which sometimes get scratches in assembly line. Can we patch up before final packing. If we use a pressurized paint canister to spray on effected area then is any pre cleaning needed?

Ratanjit Singh Sohal India

(1999)

Q. Our customers require us to assemble Powder Coated parts. Sometimes they are pitted or damaged. Is there a way to touch-up Powder Coating or Handling defects?

A. Korselman- San Francisco, California

(1999)

A. Dear Mr A Korlselman,

This query has been answered by me on an earlier letter but at the risk of repeating myself here goes:

Dissolve the same powder used in the coating in TC or any NC based thinner in which the powder dissolves. Touch up the scratched area with the resultant Paint /paste/liquid powder whatever you call it with a suitable paint brush.

Experience will give you an idea of how much your Solvent/ powder mix should be.

Thermoplastic touch up for powder coating with a glue gun

(2000)

Q. We currently powder coat wire rack for the refrigeration industry. the material is applied using fluid bed. The problem we are having is touching up the hook marks from the dipping process. Do you type/method of liquid touch-up that can fill these marks that are approx. 4 mils deep and 1/8" wide.

brian money- cleveland, Ohio

(2000)

A. I have seen a very good method of touching up hook marks like you describe. There is a manufacturer close to us who makes a thermoplastic patch stick which fits into a typical hot-glue gun. You simply melt it onto the mark like you are glueing parts together. Maybe someone close to you makes this type of product. It is much faster than waiting for a liquid touch-up to dry.

Paul Norman- Odessa, Texas

Touching up powder coating causes over-curing

(2005)

Q. Are powder coating touch-up systems commercially available? A current system for touch-ups doesn't have appealing aesthetic quality? After applying the powder to the affected area, the powder is cured, and the powder coating in the surrounding area is over-cured? Does anyone have any suggestions?

Caleb Hammons- Warner Robins, Georgia, USA

(2005)

A. Hi,
Most powder coaters use aerosol car spray paint or a small pot of car paint and brush.

Terry Hickling Birmingham, United Kingdom

(2005)

A. Caleb, it sounds like you are saying that you try to touch up powder coating flaws by re-applying powder to the flawed area and then re-curing it causing the first coat to over-cure and change color. The proper way to fix a powder paint reject is to sand (or chemically strip) the whole part, not just the bad area, and then repaint it.
There are aerosol suppliers that will match the powder you are using so that you can do touch-ups.
Some powder suppliers match their own powders in aerosol, so you might want to ask your rep if they provide that service, or maybe he can recommend someone to you.

Sheldon Taylor supply chain electronics
Wake Forest, North Carolina

(2006)

Q. How we can touch up the scratched areas on powder coated surface using epoxy ester powder / pure polyester powder? Is it advisable to spray paint to cover up the scratched areas on powder coated surfaces or what would be the solution?

M.SIVAKUMAR- Chennai, Tamil Nadu, INDIA

(2006)

A. Spot touch up is the best solution for very small areas. For larger areas, it is best to touch up with a Pu based automotive paint (gives good performance over these areas).

Amit Amembal- Mumbai, India

(2006)

Q. Mr. Amit,
Sorry for responding to you belatedly since I was out of station. First I thank you for sparing your valuable time and answering my question. Kindly tell me what paint I should use for spot touch up? Also tell me whether PU spray painted parts instead of powder coating would give the same results in all terms? Have a good day! Thank you once again.

M.SIVAKUMAR- Chennai, Tamil Nadu, INDIA

A. Hi Sivakumar. We merged your inquiry into a thread which offers lots of perspectives on the situation. However, no, a touchup will never be as durable as the original powder coating (consider that the scratch may have also scribed through the pretreatment). If you need perfection, you need to strip the powder coating and start over. Sorry.

Regards,

Ted Mooney, P.E. RETfinishing.comPine Beach, New Jersey

Need a repair spray with texture

(1999)

RFQ: I am looking for an aerosol spray that can spray out grey rough texture colour to do touch up work on texture type powder coating.

Q. We have an issue of hitting or dragging marks on office workstation legs (powder coating removes off slightly). Since its very costly to replace the legs, can anyone suggest how these marks can be removed WITHOUT affecting the powder coating

Venkat BalakrishnanQuality Engg - chennai, India

November 2014

A. Hi Venkat. Waxing/polishing sounds like the easiest approach for faintest marks. For deeper marks, the rubbing compounds and scratch removers sold in auto stores should do it. Where the powder coating is deeply scored or missing, then touching up as described by Khozema and others above should work.

Regards,

Ted Mooney, P.E. RETfinishing.comPine Beach, New Jersey

Best way to re-coat a part without affecting the color?

December 9, 2014 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. I basically have a run of parts that have been powder coated but due to the nature of the bends in the sheet metal and the way some of them were placed on the conveyor the powder did not catch on on the insides of some of these parts (inside of the bend which is not visible). Was just wondering what the best way to touch up the paint would be, manually using a brush would be pretty labor intensive and slow and sending it through to re-coat the entire part might darken the color which I cannot have. Would it be possible to just spray the inside of the bend where it didn't catch on and then cure it again?

Varun A. - Dubai, UAE

December 2014

A. Hi Varun. We appended your inquiry to an earlier thread with some helpful ideas. Remmelt Bosklopper's idea of spraying a 2-part coating (such as an automotive clearcoat) on the poorly coated and non-visible area sounded good to me :-)

Regards,

Ted Mooney, P.E. RETfinishing.comPine Beach, New Jersey

December 12, 2014

A. Partial re-spray with powder usually adds to the problem. The partial overspray onto already coated parts causes a grittiness in the coating loosing gloss. If using powder, then full respray. Don't forget adhesion. What will be the adhesion mechanism of your new top coat to the original coating? Better to sand it to get a key between coats.
Alternatively, used a matched colour liquid paint as touchup from an aerosol.

Geoff Crowleygalvanizing & powder coating shop
Glasgow, Scotland

August 2, 2015

I hear a lot of answers saying to sand before applying a second coat or color change.
From experience I'd like to add some helpful tidbits of information for anyone seeking an answer to recoating a piece that's already been coated.
If you have a media blaster / sand or other and you have experience with it, you can save a lot of time and effort by preparing the surface by hitting it with a media that won't take the powder coat off it, simply prepares it for another coat.
One of the most important things to remember when recoating is the piece might be difficult to get a connection to complete the statically charged surface. What I do when I'm in doubt is to preheat the piece at about 250 °F.
It can be tricky to manage but if you are properly set up, you will be able to do this with ease. use a low bar settings on your gun and dust it with a generous coating of the color you've selected. Put it back in the oven and bring it up to temp for 5 minutes, then shut the oven off and let everything cool untouched.
The surface coating will be very well adhered to the substrate powder coat. You can use this same method for multicolor applications, using masking tape. If you are familiar with pinstriping tape, that is the type of accuracy and delicacy it takes to work with a warm to hot precoated part. No fingers can touch the surface. have your tape prepared and your piece stable enough to work on. I have multiple fixtures from wire hangers to grates to magnets that I use to stabilize, hang or secure to work on. You might find that an assortment of magnets very handy. They can hold a hot piece through a precoat and take a fair amount of heat.
You can make electromagnets very easily that works off a switch and is unaffected by the temps normally required for general powder coating.
With a little practice and patience you will find that magnets will help the powder to adhere using them to enhance the electrostatic. Those are my helpful tidbits of intell.
I am self taught and I build hot rods. I have powdercoated parts that others said would stand up to the test of time, wear and tear, and I, as they are amazed. Through some simple enhancements you can make a bond that is virtually impenetrable through heat cycles knocks and bangs from wrenches etc, holding up amazingly well.
Practice on awkward shapes, multicolor, masking and plugging areas to keep uncoated, or to keep a base color. Have fun with it. Stop at the dollar store and buy things in the kitchen utensil department that will challenge you. Nothing ventured nothing gained.

Steve Lindsayheritage Hot Rod - Oxford Station, Ontario, Canada

Can I powder coat an uncoated area (masked off during first coat) of a powder coated cylinder?

April 14, 2016 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi,
I have an 9" diameter aluminium tube. It was powder coated successfully but I asked the engineer to mask off a strip 1" wide towards one end of the tube (the strip goes around half of the circumference of the tube, not along it).

The problem is that the engineer misunderstood my instructions and the mask goes along the bottom half of the circumference instead of the top (I can't just rotate it as there are components that are welded on that need to be at the top). Also the strip is not completely straight either and does not look great so I'm thinking scrap the masked strip idea altogether and just get him to powder coat the masked area.

My question is: is this possible? Can you powder coat aluminium a second time? will the masked area then become indistinguishable from the rest of the housing? Any advice appreciated! The coating is: Harley Davidson Engine Black Texture: =>

Thanks!

James

James Hopkins - London, UK

April 2016

A. Hi James. I think Khozema's posting is the most applicable response to your situation, but "indistinguishable" is an awfully tall order, the more so for a texture paint :-)

A. The answer is No.
If you re-coat, you will overbake the initial coat leading to brittleness and loss of properties.
Best to strip back to bare metal either chemically or mechanically and re-process with more care.
Hope this helps.
Regards,
Bill

William DohertyTrainer - Salamander Bay, Australia

June 20, 2017

Q. What is a protective coating that can be applied to a matte powder coat metal sign to help prevent scratches? A spray would be easiest for application purposes but we are open to suggestions.

The sign is already installed so sending it back to the powder coating company is not an option. Custom's belts and purses scratch the metal when they lean against the front desk.

A. Hi Mackenzie. Metal is harder than organic coatings like powder coating or clearcoats, so the problem is not 100% solvable. But the hardest coating you will be able to conveniently apply on top of that powder coating is probably a two-component automotive clearcoat (the chemical reaction makes for a harder cure than you would get from evaporation of wet paint or clearcoat, and I think you want to avoid baking or UV exposure).

I haven't tried it, but there is a two-component clearcoat in spray cans that should be worth trying if you can't get an automotive painter in there to mix and spray with professional equipment. Good luck.

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